Only the default PSI IDs are supported, other controllers fall back to
USB 3.0. Record the speed IDs the controller has: the root hub BOS
lists those, and a link without one uses the closest lower ID.
Per xHCI 6.2.2, take the parent hub slot ID and port number of SS and
SSP devices from the closest higher-rank hub.
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D52347